The present invention relates to locking devices and, more particularly, to locking devices of the dead bolt type which are actuated between the locked and the unlocked positions by application of a pressurized fluid.
Some applications require locking devices which are secure, tamper-proof and are unlikely to generate potentially dangerous signals or effects. Although the present invention should not be considered limited to a particular application, one application in which the above requirements are in effect is in igloos of the type in which ammunition and weapon systems may be stored. Such igloos typically are earth covered and include a door having as secure a locking device as possible.
It is customary to employ substantial padlocks on igloo doors to impede unauthorized entry. A need for ease of entry for authorized personnel limits the impediments which can be placed in the way of unauthorized entry. Electrically operated locking devices are attractive alternatives to padlocks in some applications because of the sophisticated coding which electrical, and especially electronic, locking devices permit. The use of electrical devices in the vicinity of sensitive explosives, such as may be contained in the above igloos, is not favored for safety reasons.